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Britain keeps its cool as the world warms up

By FRED PEARCE

Britain may be one of the few places on the planet to escape global
warming in the next half century, according to the former head of the Meteorological
Office, John Houghton. The reason is the exceptional mixing of ocean waters
in the Atlantic between Greenland and Scotland, which will absorb any local
warming caused by the greenhouse effect. The only other place where this
occurs is in the Southern Ocean around Antarctica.

Houghton made the projection while previewing the latest findings of
the UN’s Intergovernmental Panel on Climate Change at a symposium at Green
College, Oxford, last week. He chairs the IPCC’s working group on the science
of climate change. Its findings are published this week as a contribution
to the Earth Summit in June, where a convention to combat global warming
may be signed.

Houghton said the IPCC has concluded that regional changes in climate
during the past decade have ‘broadly mirrored those projected by models”
of the greenhouse effect. As predicted, warming has been greatest over the
land and least over the sea, greatest in the arctic regions and less in
the tropics. More conspicuously, there has been virtually no warming in
the seas around Antarctica and Greenland.

The seas around these two ice-covered landmasses are the only places
where surface water plunges to the ocean bottom as part of a slow global
stirring of the world’s oceans. The water and its heat do not resurface
for a thousand years.

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John Mitchell, Houghton’s colleague from the Met Office, said that other
patterns predicted by computer models and now turning up in climate records
of the past decade, ‘reinforce our confidence” that the greenhouse effect
is taking hold ofthe planet. These include reduced snow cover in the northern
hemisphere, and a dramatic increase in the amount of water vapour in the
atmosphere, especially over the tropical Pacific.

Houghton and his colleagues have reduced their projection of how much
average temperatures will rise by the year 2100 under a ‘business as usual’
scenario in which industrial gas emissions rise according to present trends.
They reduced their estimate by half a degree to around 2.8 °C. This
is mainly because the thinning of the ozone layer and sulphate pollution
in the lower atmosphere, from burning coal and oil, may be counteracting
global warming.

For the first time, the report also includes details of how far a thin
veil of sulphate pollution may be shielding many parts of the planet from
the Sun’s rays. In places, the resulting cooling is greater than the predicted
warming from greenhouse gases.

Houghton told the symposium that the worldwide accumulation of greenhouse
gases, which trap infrared radiation in the lower atmosphere, has increased
heating at the planet’s surface by 2.5 watts per square metre. But sulphate
aerosols have reduced surface warming by at least 2 watts in a wide swathe
from Britain to China, and across the Middle East and North America.

Cooling is calculated to reach a maximum of 4 watts per square metre
over the eastern Mediterranean and Middle East. The exceptional cooling
in these areas was a ‘clear-sky effect’ said Houghton. ‘Where there are
no clouds, the aerosols have a greater effect.’

Chris Hampson of ICI said the Confederation of British Industry believes
its members could cut carbon dioxide emissions by 30 per cent through good
housekeeping and investments in energy efficiency that would pay for themselves
within five years.